Lower Blood Pressure

There is no blanket ban on flying after a heart attack, TIA (transient ischaemic attack) or stroke but each airline has it’s own regulations regarding eligibility. The first step you need to take is to contact the PMCU (passenger medical clearance unit) they will advise you on your fitness to fly and assist you in filling out the necessary forms. Your medical clearance will be then considered on completion of the following medical information (MEDIF) forms. Part 1 is completed by yourself and part 2 and 3 by your Doctor.  You need to return your medical form at least 3 weeks prior to your prospective flight to ensure that you receive medical clearance in time.

How can being in an aircraft cabin affect my illness or increase my risk?

The oxygen pressure in the aircraft cabin during flight is lower than at sea level. Blood Haemoglobin concentrations rise through a fall in the plasma volume due to dehydration. Haemoglobin concentrations may rise to 200 g/l and this increased viscosity of the blood along with increased coagulability can increase the risk of stroke and venous thromboembolism (blood clot). Also sitting in one position in the aircraft cabin over a long period and not drinking enough fluids (dehydration) can cause blood to coagulate (thicken) thus increasing the risk of blood clots forming. Therefore – getting up regularly, stretching and moving your legs and feet, and drinking plenty of fluids (preferably not alcohol as this causes dehydration!) will help to decrease your risk.

 

Flying after a Heart Attack

Generally – you can fly within 2 weeks after a heart attack but this will solely depend on your recovery time and progress, and whether you have suffered any further complications since the attack.

Flying after a Transient Ischemic Attack (TIA)

If you have suffered a transient ischaemic attack (TIA) you may be allowed to fly after a 10 day period but this is provided that you have made a complete recovery, and been given complete medical clearance.

Flying after a Stroke

Generally Doctors recommend waiting for at least 3 months before flying after suffering a stroke. This is due to a vulnerability and increased risk of developing deep venous thrombosis (DVT) or pulmonary embolism (PE). DVT is a condition in which a blood clot forms in a large vein in a muscle – this is normally in the leg or pelvic region. A serious risk occurs when a fragment of this clot breaks off and becomes lodged in a blood vessel which supply’s the lungs – resulting in a pulmonary embolism (PE).

People who have not suffered from a heart attack, TIA, or stroke are still at risk from developing a DVT during a flight. This risk can be decreased by wearing ‘compression stockings’ (also known as TED or thrombo-embolic deterrent stockings).

These are worn to maintain good circulation and reduce the risk of blood clots forming in leg veins. For further information about flight stockings you can obtain a factsheet from your health care provider.

If you’ve seen the movie ‘snakes on a plane’ you may feel like you never want to fly again. However millions of Americans and people from the rest of the developed world rely on air travel both for business and leisure purposes, and giving up flying is simply not an option for most travellers.

Safest Seats on the plane

A UK study of 105 air accidents conducted by the British Civil Aviation Authority has concluded that the safest seat to occupy when flying is one within five rows of an emergency exit. This research applies to the chances of surviving an accident or other emergency situation. But what about other factors, such as health-related concerns, especially your in-flight heart and circulatory system health ? What are the most unsafe seats on the plane ?

Most Unsafe Airplane Seats for DVT

Well, apparently if you occupy a seat by the window, this doubles your risk of suffering from a potentially fatal DVT (deep vein thrombosis), or blood clot, according to a new study carried out by scientists from Leiden University Medical centre in Holland, and published by the British Journal of Haematology. If you sit in an aisle seat, then statistically there is no increased risk of DVT.

Another conclusion from the report suggests that the risks are even greater if the travellers are overweight or obese. If you fall into this category, and you occupy a window seat, then your chances of developing blood clots in the leg are an alarming six times greater than if you had been seated next the aisle. Also, flying Business Class helps to reduce the occurrence of deep vein thrombosis symptoms by up to thirty percent, according to the study.

Another major factor involved the length of the flight, with long haul flights topping the list of the highest risk options. There are a number of possible explanations for the findings :-

Reasons for Window Seat Related DVT

There are a number of possible theories for why the window seat occupancy may be responsible for the increased prevalence of DVT and blood clotting, as follows :-

• Passengers fall asleep more easily if they sit by the window
• sleeping for an extended period on a long haul flight increases the chance of developing a blood clot due to inactivity
• Window seats usually involve sitting or sleeping in a more restricted position
• Window seats offer less opportunity to move around the cabin and get exercise, without disturbing other passengers

The most serious DVT problems come if the blood clot migrates through the bloodstream to the lungs, where it can cause a blockage known as a pulmonary embolism.

Traditional DVT prevention methods may be less effective for window seat occupation

Some surprising aspects emerging from the study are that tried and trusted traditional methods used for preventing air travel related DVT may not be as effective as has been thought for window seat occupying passengers. Air travellers have increasingly been advised to :-

• wear elastic stockings during the flight
• avoid alcohol
• drink plenty of water

However the Leiden University research suggests that drinking plenty of water (or tea) during the flight made no difference to the risk of DVT, and amazingly, wearing elasticated stockings actually increased the risk of developing a DVT. Just to buck the trend completely having a small amount of alcohol – a single alcoholic drink appeared to protect against developing a blood clot.

British Heart Foundation Reaction and Advice

It is interesting to note the reaction of the British heart Foundation (BHF) to this research. Professor Jeremy Pearson, from the BHF commented that ‘There were not enough passengers in this study to conclude anything dramatic. All the current guidance to passengers is based on common sense.’ This is apparently due the limited scale of the passenger numbers, with a total of 188 passenger medical diagnoses, of which 80 people had contracted a DVT and the remainder had not.

The current air travel advice from the British Heart Foundation website is as follows :-

‘There is a low risk of developing a DVT while travelling by air. Do not take aspirin or any other medication to thin the blood without first getting advice from your doctor. If you have previously had a DVT or a clot in your lungs, or if you have recently had surgery under general anaesthetic, you have a higher risk of getting DVT than other people, and you should get medical advice before flying. Your doctor will give you advice on how to prevent a DVT while travelling by air based on your individual medical condition. If you have been advised to wear compression travel socks, it is important that you have your legs measured to help you to choose the right size. If the socks are very tight, they can do more harm than good’. 

DVT Definition (Deep Vein Thrombosis)

DVT is a disease of the circulation, often associated with air travel. The medical term for a DVT is a venous thromboembolism. Our blood needs to be able to clot in order to provide the necessary protection for the body against severe loss of blood from an injury to a vein or an artery. However, blood can sometimes form clots whilst inside a blood vessel, which is the definition of a Deep Vein Thrombosis (DVT).

What causes DVT?

DVT causes can be many and varied. Blood flow through the deepest veins in the legs is relatively slow. This presents an increased risk of a solid clot forming, which can cause a partial or complete blockage in the vein. Although Deep Vein Thrombosis (DVT) can sometimes occur spontaneously in normal veins, without any obvious underlying cause, the risk of developing DVT is increased by the following surprisingly high numbers of risk factors :-

* Inactivity or Immobility
* Previous blood clots or DVT in the leg, or vein damage
* Medical and genetic conditions
* Major Surgery
* Broken leg
* Pregnancy
* Contraceptive pill use
* Hormone replacement therapy (HRT)
* Obesity
* Smoking
* Age – over 40 years
* Cancer
* Varicose veins
* Family history of DVT
* Paralysis
* Air travel

DVT Symptoms

Quite often there are no Deep Vein Thrombosis symptoms at the onset of the condition, although where they do appear, they may develop rapidly. The problem may only become apparent when a crisis develops into a medical emergency, and the blood clot reaches the lungs, where it becomes what is known as a pulmonary embolism. A DVT usually, although not always, affects only one leg. The thrombosis symptoms of a DVT in the leg include:-

* swelling – suddenly and in one leg
* pain in the leg
* warm skin
* tenderness
* redness, particularly at the back of the leg, below the knee.

Occasionally some of the surface veins become more visible through the skin, and there may also be some pain on flexing the foot upwards.

How is DVT diagnosed?

There can be many causes of a painful or swollen leg, which means that it can be difficult for a doctor to successfully perform a first time DVT diagnosis. If you have some of the DVT risk factors listed above, and your doctor suspects that you may have a DVT, they will usually recommend that you have some urgent tests performed, which will normally be carried out in a hospital, or possibly a specialist anti-coagulation clinic.

DVTs are usually detected by ultrasound, which is capable of detecting even the smallest blood clots. If a doctor suspects a DVT he or she will usually request an urgent ultrasound test, and a follow-up blood test. There is a special blood test known as the D-dimer test, which is capable of detecting fragments of a blood clot that have broken up, and present within the blood stream. This gives a reliable indication that a person may have developed a DVT.

If the results of an Ultrasound and D-dimer test cannot confirm a diagnosis of DVT, a venogram might be used. This is a more detailed test that involves a contrast dye being injected into the vein in your leg. An X-ray is then used to see whether the dye is flowing through your vein, or if it is blocked by a blood clot.

Is DVT dangerous?

DVTs themselves are not dangerous, but they are associated with complications which can become life threatening, or prove fatal. The most common serious complication is a pulmonary embolism, which occurs in approximately 30% of cases of DVT. This is where a part of the blood clot in the leg vein breaks off and travels through the blood stream to the lung, where it becomes lodged, causing chest pain and severe breathing difficulties.

Pulmonary embolism, is a common cause of sudden, unexpected death. A severe pulmonary embolism can cause the lungs to collapse, and result in heart failure. If left untreated, 10% of people die from pulmonary embolism.

More rarely, a part of the clot may also lodge in other organs including the brain, where it can lead to a stroke.

Deep Vein Thrombosis Treatments

Two thirds of people diagnosed with a DVT require initial treatment at a hospital, or possibly an anticoagulation clinic. The aim of the DVT treatment is to dissolve the blood clot and prevent further clots from forming. The primary DVT therapy is with anticoagulant medicines such as Heparin or Warfarin which thin the blood, allowing it to flow more freely. Inactivity and bed rest is discouraged and patients are encouraged to move around as much as possible. Regular blood tests are performed monitor the effectiveness of the treatment and to reduce the risk of a haemorrhage.

Painkillers and heat applied to the area may also be advised for relief of symptoms of a DVT, and compression stockings are often worn to cover the length of the whole leg to give support to the veins and reduce swelling.

As well as wearing compression stockings, you may be advised to raise your leg while you are resting, as this helps to reduce the pressure in the veins of the leg, and also helps tp prevent blood and fluid from gathering in the leg.

Occasionally a doctor may recommend dvt surgery to remove a deep vein clot. The procedure is called venous thrombectomy. This is usually necessary only in the case of a severe form of DVT called phlegmasia cerulea dolens, which does not respond to the non-surgical treatments described above. Phlegmasia cerulea dolens, if not adequately treated, can cause gangrene, which is when the tissues do not receive sufficient oxygen, and subsequently die. Gangrene is a very serious condition that may result in the amputation of the affected limb.

It should be noted that Aspirin is not used to prevent DVT. (Aspirin is widely used to help prevent blood clots in arteries which can cause strokes and heart attacks. However, aspirin does not seem to be very effective at preventing blood clots in veins.)

DVT Prevention – How to avoid getting a DVT, especially when travelling by Air

Prophylaxis is a medical term used for ‘prevention’. DVT prophylaxis is always preferable than having to deal with consequences of developing the condition. There are certain precautions that you can take to avoid getting a DVT.

If possible, avoid long periods of immobility such as sitting in a chair for many hours to avoid the blood ‘pooling’, and to get the circulation in the legs moving.

Major surgical operations are known to be a risk for a DVT – particularly operations to the hip, lower abdomen, and leg. You may be given an anticoagulant such as a heparin injection just before having an operation to help prevent a DVT. An inflatable sleeve connected to a pump to compress the legs during a long operation may also be used. It is also common practice to get you up and walking as soon as possible after an operation.

If you are planning to travel by air, especially on a long-haul flight, the the following specific tips can significantly reduce your chances of developing a flight or travel related DVT :-

* drink plenty of water
* avoid excessive alcohol as it can lead to dehydration
* avoid taking sleeping pills as it can cause immobility
* perform simple leg exercises, such as regularly flexing your ankles. Most airlines provide information on suitable exercises to do during your flight
* take occasional short walks, when in-flight advice suggests it is safe to do so
* take advantage of refuelling stopovers where it may be possible to get off the plane and walk about
* wear elastic compression stockings.

After DVT

After a DVT has been diagnosed, persistent symptoms may occur in the affected part of the leg. In order to minimise the risk of further complications you may be advised to wear a compression stocking for many months or even years. Also, by following some simple additional steps, you can further minimise the possibility of longer term problems as follows :-

* Raise your leg when you are resting to reduce the pressure in the veins in the affected leg.

* Raise the lower end of your bed by a few inches so that your foot and calf are slightly higher than your hip whilst you are sleeping.